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posted by chromas on Tuesday April 24 2018, @06:02AM   Printer-friendly
from the \ dept.

"Super-Earth" planets are giant-size versions of Earth, and some research has suggested that they're more likely to be habitable than Earth-size worlds. But a new study reveals how difficult it would be for any aliens on these exoplanets to explore space.

To launch the equivalent of an Apollo moon mission, a rocket on a super-Earth would need to have a mass of about 440,000 tons (400,000 metric tons), due to fuel requirements, the study said. That's on the order of the mass of the Great Pyramid of Giza in Egypt.

"On more-massive planets, spaceflight would be exponentially more expensive," said study author Michael Hippke, an independent researcher affiliated with the Sonneberg Observatory in Germany. "Such civilizations would not have satellite TV, a moon mission or a Hubble Space Telescope."

https://www.space.com/40375-super-earth-exoplanets-hard-aliens-launch.html

[Also Covered By]: GIZMODO

[Paper]: Spaceflight from Super-Earths is difficult

[Related]: 10 Exoplanets That Could Host Alien Life


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  • (Score: 2) by zocalo on Tuesday April 24 2018, @02:44PM (3 children)

    by zocalo (302) on Tuesday April 24 2018, @02:44PM (#671176)
    Assuming you can build a balloon large enough to lift the required payload, then sure. We've certainly been able to get balloons to the edge of space so that people can jump out of the capsule for the ultimate in freefall thrills. We've also launched aerospace craft from below other aircraft - X-15 through to Virgin Galactic - so again, it's not completely "out there". It's going to be an awfully large balloon though, and you're going to be going through a correspondingly large volume of helium (presumably) in the process, so unless helium is much more plentiful in their world (quite possible, if the higher gravity has limited the bleed to space) or they get very good at retrieval of the balloon and gas (also possible) then they might hit "peak-helium" rather quickly. Like all the other solutions, the specifics of the environment and technological path are the key, but it does seem like it might not be quite so gloomy a proposition as TFA makes out, provided that you're prepared to allow for some approaches that we might consider sub-optimal in our environment.
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  • (Score: 2) by Immerman on Tuesday April 24 2018, @07:47PM (2 children)

    by Immerman (3985) on Tuesday April 24 2018, @07:47PM (#671289)

    Why use helium? Hydrogen is a LOT more plentiful, slightly more potent, and not dramatically more dangerous as long as you treat it with due respect (LOTS of airships used hydrogen safely for years, the Hindenburg was never designed to do so - it was designed to use helium). There's also no particular reason to "use it up" - it's quite possible to have both a balloon and pressure tank, and pump your lift gas between them to control buoyancy.

    And building a large enough balloon is a safe assumption for a species even 100 years more technologically advanced than us, we could probably do it today - heck, we've figured out how to mass-produce graphene, which is probably as good as it gets for balloons. If you want to lift a 1000kg point mass (to sidestep payload buoyancy considerations) on Earth you need a balloon large enough to hold a bit more than 1000kg of air - at 1.225 kg/m^3 that's 816 cubic meters, or a sphere roughly 12m across. On Venus air density is 67 kg/m^3, so to get the same lift you'd only need about 15m^3, or only 3m across. Of course you need a bigger balloon as you get closer to vacuum, but that's why the Airship-to-orbit folks plan a transfer from their "deep atmosphere" to their orbital one.

    And again - it doesn't matter what the gravity is, your balloon just has to displace a greater than-payload mass of air, buoyancy does all the work. The only place the force of gravity factors in is the necessary strength of the balloon to support your payload - which if you're using graphene might have to be dozens of atoms thick.

    • (Score: 0) by Anonymous Coward on Wednesday April 25 2018, @07:47AM (1 child)

      by Anonymous Coward on Wednesday April 25 2018, @07:47AM (#671539)

      The hydrogen wasn't the problem with the Hindenburg anyway. Hydrogen burns with a faint blue flame, not the large yellow-orange flames the Hindenburg burned with.

      The Hindenburg was covered in a conductive paint due to problems with static discharges. That paint was basically thermite, which just happens to burn with huge yellow-orange flames.

      • (Score: 2) by Immerman on Thursday April 26 2018, @02:48AM

        by Immerman (3985) on Thursday April 26 2018, @02:48AM (#671994)

        True, but the Hindenburg is pretty much why hydrogen, and airships for that matter, went out of style. Facts are irrelevant once the media adopts a narrative.